Reverse emulsion breaker copolymers

Abstract

The present invention generally relates to methods for resolving water and oil emulsions in the produced fluid of an oil production system comprising adding a structured copolymer reverse emulsion breaker to the produced fluid of the crude oil production system in an amount effective for resolving an oil-in-water emulsion. In particular, these methods for resolving an oil-in-water emulsion can be used in separation processes where the oil and solids in the produced fluid are separated from the produced water in the produced fluid.

What is claimed is: 
     
       1. A method of resolving a reverse emulsion in produced fluid of an oil production system comprising adding a reverse emulsion breaker to a produced fluid of the oil production system in an amount effective for resolving the reverse emulsion, the reverse emulsion breaker comprising a structured copolymer derived from the monomers of Formulae 1, 2, and 3: 
       
         
           
           
               
               
           
         
       
       wherein
 R 1 , R 2 , and R 3  are independently hydrogen or alkyl; 
 R 4 , R 5 , R 6 , R 7 , and R 8  are independently alkyl; 
 A is independently —NH— or —O—; 
 p and q are independently an integer from 1 to 6; and 
 the weight average molecular weight of the structured copolymer is from about 20,000 to about 2,000,000 Daltons. 
 
     
     
       2. The method of  claim 1  wherein A is —NH—. 
     
     
       3. The method of  claim 2  wherein the weight average molecular weight is from about 100,000 to about 850,000 Daltons. 
     
     
       4. The method of  claim 1  wherein the structured copolymer has a viscosity of about 200 cP to about 105000 cP at a concentration of from about 5 wt. % to about 95 wt. % in a solvent. 
     
     
       5. The method of  claim 4  where the copolymer has the viscosity of about 500 cP to 5,000 cP. 
     
     
       6. The method of  claim 1  wherein the copolymer is prepared in aqueous solution, inverse emulsion, dispersion, or as a dry polymer. 
     
     
       7. The method of  claim 6 , wherein the structured copolymer is prepared in aqueous solution. 
     
     
       8. The method of  claim 1  wherein the structured copolymer is a branched, hyperbranched, comb, dendrimer, or star polymer. 
     
     
       9. The method of  claim 1  wherein the reverse emulsion is an oil-in-water emulsion, a water-in-oil-in-water emulsion, or a combination thereof. 
     
     
       10. The method of  claim 9  wherein the reverse emulsion is a water-in-oil-in-water emulsion. 
     
     
       11. The method of  claim 10  wherein R 1 , R 2 , and R 3  are independently hydrogen or methyl. 
     
     
       12. The method of  claim 11  wherein R 1  is hydrogen, R 2  is hydrogen, and R 3  is methyl. 
     
     
       13. The method of  claim 12  wherein R 4 , R 5 , R 6 , R 7 , and R 8  are independently methyl, ethyl, propyl, butyl, pentyl, or hexyl. 
     
     
       14. The method of  claim 13  wherein R 4 , R 5 , R 6 , R 7 , and R 8  are methyl. 
     
     
       15. The method of  claim 14  wherein q and p are independently 1 to 3. 
     
     
       16. The method of  claim 1  wherein R 1  and R 2  are hydrogen; R 3  is methyl; R 4 , R 5 , R 6 , R 7 , and R 8  are methyl, and p and q are 2 or 3. 
     
     
       17. The method of  claim 1  wherein the reverse emulsion breaker is water-soluble. 
     
     
       18. The method of  claim 1 , wherein the produced fluid is from a steam-assisted gravity drainage production system. 
     
     
       19. The method of  claim 1  wherein the effective amount of the reverse emulsion breaker is from about 10 ppm to about 250 ppm based on the total volume of the produced fluid. 
     
     
       20. The method of  claim 1  wherein the structured copolymer comprises from about 65 mole percent to about 90 mole percent of the repeat units derived from the monomer of Formula 1, the structured copolymer comprises from about 0.5 mole percent to about 2 mole percent of the repeat units derived from the monomer of Formula 2, and the structured copolymer comprises from about 10 mole percent to about 35 mole percent of the repeat units derived from the monomer of Formula 3 in the structured copolymer.